Smokey

Forgive me if this topic has been discussed before (I don't post all that much), but I was surfing around the Web and wound up at this site: https://www.dynamicbicycles.com/ A chainless bike?? What's up with that? Have any of you guys/gals ever heard of such a thing? Do you own one? Ever ridden one?

Also, what's your opinion on this radical departure from the traditional (and please...no soap boxing. Just an honest opinion about the technology...thanks!)???

It also features (has to) an internal-gear hub. That makes two departures from the original. The company is located in MA, so I'm not sure they'll have a store on the West Coast that sells them (if ANY store sells them, that is...they may be strictly Internet).

Anyway, just thought it was kinda cool and wanted your opinions. I may also post to the Mountain Bike and Repair groups.

Thanks!

C Law

Radically inefficient and an answer to a question that nobody asked.

DEK

How about this one? It uses a "rubber belt drive". Basically a rubber chain.

https://www.vivavi.com/catalog/produc...roducts_id=723

I personally don't think it's worth anywhere near $1,300.

monkey69

we had that discussion in the last 2 weeks or so ,just scroll through the last couple of pages and youl find it .
btw. for me this seems to be as much of a great invention as the smokless cigarrett

bostontrevor

https://www.bikeforums.net/commuting/52599-chainless-shaft-drive-anygood.html

Shaft drive doesn't really solve any problems that aren't solved by a full chaincase, it's an idea whose time has never come. It's more than a century old but every few decades someone rediscovers it and thinks they've really got something.

I've ridden a Dynamic and it felt like a bike. The drivetrain felt remarkably smooth but nothing magical.

Internally geared hubs are almost as old. Unlike shaft drive, they have some real utility. They're not as efficient or as light as a derailleur system but they are virtually maintenance free, well suited to messy conditions, very durable, and can be shifted even when not moving.

dbg

I'm thinking it might solve the problem of all my right pant legs getting greasy on my commute. I'm already running a nexus 7 rear hub, dynamo front hub, and carrying a 20+ lb backpack, so a little more load won't hurt much. Long term trial would be needed to see if maintenance were easier. "Just shoot grease in through the nipples regularly" they told me when I test rode one. It felt no different than a chain drive.

..Or maybe a chain guard would accomplish the same thing.

RubenZ

to be honest I think its stupid. as I said before, what next motors on our bikes.

a2psyklnut

Heavy, inefficient and prone to damage.

The bicycle has remained virtually the same (basic design mind you) because it's simple, very efficient, lightweight and easy to maintain.

You'll be hard pressed to find a drive train system that works as well as a chain and cog.

Eventually? Yes, probably. But for now? NOPE!

bostontrevor

Exactly, and do it better besides.

The driveshaft is really heavy ("under 4 lbs") which is pretty damn heavy compared with a chain and even a chaincase. On top of that, you can't gear up or gear down the unit the way you can with a chain drive by swapping in different sized cogs or chainrings. Dynamic's suggestion is that an owner who wanted this flexibility would purchase additional shaft units at the cost of $80 apiece.

Chaincases have been around and in continous popular use for a long time. They're a well tested technology that solves all the problems a shaft drive solves and do so in a better fashion. Shaft drives look cool, I'll give you that, but that's about it.

RubenZ

Yup, thats why motorcycles to this day still use the chain system.

Kennetht638

A chain drive is 98-99% efficient

A belt drive is probably closer to 75-80% efficient because a belt will not wrap around a pulley as easily as a chain will wrap around a sprocket.

A shaft drive is um...not very efficient at all compared to a chain (I have no actual numbers) because:
1) It uses bevel gears which are inherently inefficient because they transfer force in directions that are not the direction of motion.
2) Friction between gear teeth is inevitable because as they spin, they rub against each other, and for a low-tooth-count gear like what is probably on that bike, the contact is pretty large.
3) Shafts can twist (wind up) though I'm not sure how much that matters on a bicycle

smoothshady

With 98% to 99% efficiency, our shaft drives bikes perform more consistently than chain and derailleur bikes that range in efficiency from 75% for poorly tuned systems up to 97% for perfectly tuned systems. - from website
Sounds interesting but probably needs more time to mature. I think Shimano just came out with a new 8 speed nexus hub. Tinkering with the drive train looks like it would be much more complicated, but on the other hand it shouldnt need as much service.

phinney

Could be a suitable product for the market they're aiming at. Depends on how good a job they've done implementing the shaft drive.

Normally a shaft drive could be expected to be heavier, less efficient, and more costly than a chain drive. Benefits could be lower maintenance and no exposed lubricant. I didn't see from their information how they are providing lube to the bevel gears.

A modern toothed belt drive is very efficient - better than a poorly lubricated chain. Seems like it would be better to use a belt drive for the same benefits as a shaft but simpler, lower cost (both to develop and manufacture), no lubricant, and lighter.

Still, especially when combined with an internally geared hub, not as efficient, light or versatile as our chain drive derailleur systems. Could make a great commuter though.

Killer B

In a word....
GIMMICK

wannaride

As the owner of several shaft drive BMW motorcycles, I am intrigued by the idea. A shaft drive motorcycle has a much lower need for drive train maintenance but there is a weight and efficiency cost. If shaft drives had the efficiency levels referenced on the web site then Moto GP bikes would be using shaft drives. However the use of the bike as a commuter bike seems a particularly good application. What I wonder about is why there seems to be no price listed on the web site?

I had found another shaft drive bike that I found interesting:

jeff williams

The bikes look lousy. The 'suspension' bike they market is well...poorly set up component wise and geometry\linkage. The drive ??? well it's kinda cool, I still would not buy them simply as they have little clue what to spec a bike out for in regards to components.
https://www.dynamicbicycles.com/buy/Bikes.php?prodid=47 uhh, no.

The comfort bikes, maybe. A commuter that requires little maintenance might be good for some people who have little interest in the maintenance\simplicity of chain driven bikes.

What happens when the 'advanced' drive has problems? Will a bike mech even work on this system?

timmyquest

Shaft driven bikes are nothing new actually. Infact i belive the very first "modern" bikes were shaft driven

RicMic

Wannaride, press the "buy" button. They're 550 to 750.

Maelstrom 

All threads regarding this have been merged. Hence the reason some of you find your posts in the mechanics forum.

Cheers

Maelstrom
MOD

dannymelancholy

Seen this - https://www.biomega.dk/biomega.aspx- ?

Aesthetically pleasing but I suspect that is where it ends.

kymtb

You're not totally right on this point. I come from the motorcycle world and can tell you that the best most dependable bikes are without chains. Why??? Because a shaft has less maintanence, can handle more power, and will outlast any chain made (i.e. Goldwing, ST11/13, FJR, any BMW, Concours, ETC.). I know the next question. What about off road bikes? Well have you ever heard of the BMW GS. It's the ultimate in adventure touring. It's won the Paris/Dakar race numerous times and its shaft driven.

I really believe that the shaft drive is the way to go. With some inhancemets what you see in the link above will out preform any chain and cog system available.

spider-man

Most (but not all) racing motorcycles use a chain-drive system. There are some exceptions, such as Moto Guzzis (which have had great success in the past) and BMWs, both of which are shaft-drive, for the most part. And Buells, which have a belt-drive, also are raced.

But the premier racing leagues are dominated by chain-drive motorcycles, primarily because of the weight savings and ease of adjustability. Weight is even more important on a machine in which the power is human supplied, at least if you want to ride fast.